If it would not pose an undue hardship, the employer must grant the accommodation.An employer does not have to accommodate an employee's religious beliefs or practices if doing so would cause undue hardship to the employer.
This applies not only to schedule changes or leave for religious observances, but also to such things as dress or grooming practices that an employee has for religious reasons.
“When the Chief Justice read me the oath,' he [FDR] later told an adviser, 'and came to the words "support the Constitution of the United States" I felt like saying: "Yes, but it's the Constitution as I understand it, flexible enough to meet any new problem of democracy--not the kind of Constitution your Court has raised up as a barrier to progress and democracy.” ― Susan Quinn, “Don’t ever rule out the option of U-turn in your life, because one day you will need it!
The moment you realize that you are going to the wrong direction, turn to the right direction instantly, with a beautiful U-turn!
This means an employer may be required to make reasonable adjustments to the work environment that will allow an employee to practice his or her religion.
Examples of some common religious accommodations include flexible scheduling, voluntary shift substitutions or swaps, job reassignments, and modifications to workplace policies or practices.